Jim Parsons reveals that there were two major changes made to The Big Bang Theory when the pilot was reworked. Before CBS officially ordered the nerd-centric sitcom, the network requested co-creators Chuck Lorre and Bill Prady to retool the comedy. Much has been said about Amanda Walsh's Katie being replaced by Penny and the addition of Howard and Raj, but as it turns out, there are other big alterations done to the series.
Speaking on Dinner's On Me With Jesse Tyler Ferguson, Parsons discusses changes made to the original The Big Bang Theory pilot.
Parsons discusses numerous adjustments that were made when the pilot was reshot. He reveals that aside from the cast changes, the show's setting and color palette were also changed.
They changed the location to the East Coast to the West Coast, and they completely overhauled the color palette. The original pilot looked a lot like our show but it looks as if you threw a CPF filter on it and covered it with cobwebs.
The Big Bang Theory's location is integral to the show's storytelling. Granted that it didn't typically film outside a sound stage, but being in Los Angeles was a big factor in the comedy. The setting had Sheldon and his friends all working at Caltech. Penny also moved to California from Nebraska in the hopes of becoming an actress. Additionally, many of The Big Bang Theory's great cameos relied on the California setting.
It's difficult to imagine The Big Bang Theory being set on the East Coast. Parsons didn't say where exactly it would have been set, but considering the show's premise, it could be somewhere near another prestigious academic institution. Massachusetts is the home of MIT and Harvard, which fit the bill, but it isn't an entertainment hub to justify Penny's introduction. Meanwhile, Columbia in New York may have been an option, but it just wouldn't have the same impact as Caltech, considering Sheldon and the rest's specializations.
Overall, it's for the best that The Big Bang Theory was moved from the East Coast to the West. Aside from the narrative implications of the change, there were already a lot of iconic ensemble sitcoms that focused on friendships that take place in that setting. Being in Pasadena somehow separated Sheldon and his group from them.